PRECEDENTIAL

UNITED STATES COURT OF APPEALS FOR THE THIRD CIRCUIT

_______________

No. 16

- 3667

_______________ CHARLES WESLEY BLACKLEDGE, Appellant

v.

OLGA GRIGORIEVNA BLACKLEDGE

_______________ On Appeal from the United States District Court for the Western District of Pennsylvania ( W.D. Pa. No. 2

- 16

- cv

- 01004 ) Honorable Nora B. Fischer , District Judge

_______________ Argued: May 19, 2017

Before: AMBRO

, KRAUSE, and NYGAARD

, Circuit

Judges

(Opinion Filed: August 3, 2017 )

James C. Martin, Esq. Reed Smith 225 Fifth Avenue, Suite 1200 Pittsburgh, PA 152222 Michael P. Yingling, Esq. (Argued) Reed Smith 10 South Wacker Drive, 40th Floor Chicago, IL 60606

Attorney s for Petitioner

- Appellant 1

Barbara B. Erns berger , Esq. (Argued) Behrend & Ernsberger 355 Fifth Avenue Suite 1200, Park Building Pittsburgh, PA 15222

Attorney for Respondent

- Appellee

_______________
OPINION OF THE COURT

_______________ KRAUSE, Circuit Judge

.
Petitioner , a German resident, appea ls the denial of his petition alleging that his wife wrongfully retained their then

eight

- year

- old son in the United States in violation of the Hague Convention on the Civil Aspects of International Child

1 We express our gratitude to Appellant’s counsel for accepting our appointment of this matter and for their excellent briefing and argument in this case. Law yers who
act pro bono fulfill the highest service that members of the bar can offer to indigent parties and to the legal profession.3 Abduction. Because we conclude that

, to the extent an agreement between the parties can be gleaned from the record, the parents ’ shared intent was that the child would move to the United States not for a transient visit, but with a settled purpose, and because the child had acclimatized to his life in the United States at the time of the retention , the United States was then his habitual residence and the retention was not wrongful under the Convention. Accordingly, we will affirm.

I. Factual Background

A. J.B.’s Early Years and Initial Two

- Year Residen ce in Pittsburgh

J.B. , a United States citizen, was born in the Ukraine in 2008 to Petitioner Charles Blackledge, a United States citizen who currently resides in Berlin, Germany

, and Respondent Olga Blackledge, a Ukrainian citizen and lawful permanent re sident of the United States who currently resides in Pittsburgh , United States . For the first three years of J.B.’s life

, the family lived in Kharkiv, Ukraine

, and Dublin, Ireland, while also spending some weeks in Vilnius, Lithuania. In the spring of 20 11, when the family was staying in Lithuania and then Ukraine

, Petitioner secured a job as a patent agent in German y at about the same time Respondent was accepted to a Ph.D. program at the University of Pittsburgh. The family left Ukraine and

, after a se ven

- week

summer holiday in Munich, Germany, Respondent and J.B. moved to Pittsburgh and lived for the next two years separately from Petitioner , who lived and worked in Berlin, Germany, while regularly visiting and communicating with J.B. According to Pet itioner, the plan was for the family to eventually reunite

— either Respondent would finish her4 coursework in Pittsburgh and go to Germany or Petitioner would use his position in Germany “as a stepping stone to get back to the [United States]. ” J.A. 240.

I n the summer of 2013, after Respondent and J.B. had lived in Pittsburgh for two years , J.B. underwent cardiac surgery at the Children’s Hospital in Pittsburgh. Petitioner
went to Pittsburgh to be with J.B. during his recuperation and to seek jobs in the U nited States. When those efforts proved fruitless

, Petitioner decided to return to Germany and Respondent agreed to join him

, both because she had agreed

, before the initial move to Pittsburgh, to move to Germany for two years and because she was financia lly unable to support herself at that point

. Respondent then arranged for storage of toys, books, furniture, and other belongings with a friend in Pittsburgh, and Petitioner, Respondent

, and J.B. moved together to Berlin, Germany

, in August 2013. For J.B ., this was the first time he had ever been to Berl in or ever resided in Germany.

B. J.B.’s Move to Germany

After the move, Respondent continued to pursue her Ph.D. studies at the University of Pittsburgh

, remotely, and J.B. was enrolled in the J.F.K. Sch ool, a public school “founded in conjunction [with the] American Embassy and German Governme n t” with a “bilingual/bicultural” focus, intending to provide American students with an “easier time to adjust to the [ir] German ” residency while still “preser v[ing ] their language and continu[ing] to work on their language skills and all of the subjects in English.” J.A. 430

- 31. J.B. also attended an afterschool program at J.F.K., where students could play and do their homework, joined a soccer team, and played ch ess at the Russian House.5 In August 2015

, when J.B. was seven years old

, Respondent sought to return to Pittsburgh to complete the fin al phase of her Ph.D. program. By this point, according to both parties, the marriage had become acrimonious

, and,

acco rding to Respondent , they had “agreed that [they would] divorce” and that it was only “a matter of time [as to] when.” J.A. 421

- 22. While the nature of the parties’ disagreement over J.B.’s continued residence underlies this appeal and will be discussed in more detail below, Petitioner initially agreed that Respondent and J.B. would return to Pittsburgh

, and they requested a one

- year leave of absence for J.B. from the J

. F

. K

. S chool and secured German visas for themselves and J.B. that were valid through 2 018. Given the belongings they had stored in Pittsburgh in August 2013

, Respondent and J.B. opted to leave in Germany items that were difficult to transport , such as toys, Legos, and a bike

, when they returned to Pittsburgh in August 2015

.
C. J.B.’s Ret urn to Pittsburgh
Back in Pittsburgh, J.B. attended second grade in the 2015

- 20 16 school year and , according to his teacher

, “performed as a wonderful second grader,” earning, cumulatively, at the end of the year As in spelling, handwriting, math, and gram mar, and a B in reading, and finishing the year on “academic high honor roll.” J.A. 328

- 30. J.B.’s teacher described him as a “well

- behaved” child who “followed rules and routines easily,” “made friends easily,” J.A. 330, was “[k]ind, happy, loving, eage r to learn,” and was generally “well

- adjusted

, ” J.A. 334. Despite an initial deficiency in reading, J.B. finished the fourth quarter with “an excellent grade,” showing what his teacher termed “dramatic improvement” in his rea ding level throughout the
year

. J.A. 333, 451. J.B.’s love of reading extended beyond6 the school year, when J.B. joined a summer reading challenge, completing the fifteen

- book assignment by July 5

, two months ah ead of the August 31 deadline.

J.B. was also a member of a four

- student robotics club, organized by a parent of one of his classmates. The team met every Saturday or Sunday afternoon when the students would design missions and submit the mission to a robotics competition , winning first place in Pennsylvania and twenty

ninth in the United States

. J.B. was tentative at first, because he didn’t know how to program the robot and thought the tasks were “impossible,” but by the end “he was . . . so excited” by the project, and he was able to explain his favorite mission and how th e students accomplished it. J.A. 355

- 56. J.B. and the classmate whose mother had organized the robotics club “stayed friends after the robotic project” ended, playing Legos and soccer together. J.A. 358

.
In addition, J.B. bonded with his teammates on hi s swim team , which ran for three trimesters

— from September through December, January through April, and May through July. The goal for students on the team was to master the four competitive strokes so that they would be able to do th em “correctly if they decide[d] to compete.” J.A. 3 69

- 70. At the start of the year, J.B. was “able to swim the length of the pool free style” and had “a pretty good breast stroke kick, but his endurance

— swimming the l ength of the pool was difficult

. ” J.A. 371. B y spring , h owever, he was able to compete in four meets , “better[ing] his times pr etty much every meet ” and

, by summer , “he was able to swim all four strokes,” do “flip turns,” and “dive

. ” J.A. 371

- 72

.
J.B. made many friends in Pittsburgh and enjoyed play dates, b irthday parties, video

- gaming, playing soccer, playing7 card games

, sleep overs, and other outings with various young people. J.B.’s own birthday party, when he turned eight in June 2016, was attended by many of those friends. Respondent’s friends and coll eagues also developed a bond with J.B., en

j oying dinners together, attending u niversity events and spending weekends and holidays together, going to the park, attending theater festivals and puppet shows together, and generally playing with and babysitting J.B.
Respondent and J.B. also explored the broader Pittsburgh environs, including trips to Erie, Pennsylvania

, Frank Lloyd Wright’s Fallingwater in Mill Run, Pennsylvania

, and Pittsburgh’s four Carnegie Museums

. They also became members of a local mu seum called the Mattress Factory wh ere J .B. enjoyed “showing off his knowledge

. . . to his friends,” whom he sometimes invite d to join him . J.A. 446

- 47. J.B. ’s interests extended as well to sports, and he became familiar with the local sports teams and

was a fan of the Pittsburgh Penguins hockey team and the Riverhounds soccer team

.
D

. Parents’ Dispute Over J.B.’s Continued Residence

Within the first month of J. B.’s stay in the United States, Petitioner sent Respondent an email, referencing job applica tions he had sent to the United States and elsewhere

, and indicating that he might be moving to another country so that J. B. would not be returning to Germany at all

. Respondent assured Petitioner that J.B. “is pretty happy in Pittsburgh, so by the end of the year, going back to Berlin might not be exactly what he wants.” J.A. 199. Petitioner replied to this email but did not comment on, or reject, the possibility of J.B. remaining in Pittsburgh.8 However, f

ive months later, i n February 2016, Petitioner initiated a series of emails with Respondent that form the bulk of the record of the parties’ shared intent as to J.B.’s habitual residence. These began with Petitioner’s request that Respondent “confirm [her] commitment to our agreement” that J.B. would return to Germany for the 2016

- 17 academic year

. J.A. 188

- 90. For her part

, the Respondent did not deny the existence of an agreement but asked the Petitioner to “reconsider it,” J.A. 172, explaining

, “ I d o not think . . . it i s a good idea for a child [ J.B. ’s ] age to live with one parent for a year, and with the other for a year

, ” J.A. 181. Th at agreement, Respondent stated, “presupposes . . . yearly adaptation to living with different parents [which] is psychologically disadvantageous” to J.B.

, and ur ged Petitioner to consider J.B.’s well

- being, J.A. 177 , suggesting that Petitioner move “somewhere close” so that they could both “take care of [J.B.] on a permanent basis” and not “change [ J.B.’s ] permanent caregiver every year.” J.A. 181.

In respons e, Petitioner observed that Respondent had not expressed any concerns about J.B. “ spend [ing] alternate years with us when the agreement was made

. ” J.A. 178. And while Petitioner acknowledged Respondent’s “concerns about stability of dwelling

, ” he explaine d that he did not “think there [we]re better options than mainta ining [ their ] previous agreement, ” J.A. 179 (emphasis omitted)

, which he characterized as: “ [J.B.] would go with you to Pitt [sburgh] and return to me for 2016

- 2017 academic year. Then back to
you . . . .” J.A. 176. I n subsequent correspondence, Petitioner advised Respondent to “prepa re [herself] for fulfillment of [the] agreement that [J.B.] returns to [Respondent] for 2016

- 2017, ” reassuring her

, “You’ll have him again in 2017, ” J.A. 168. A nd i n May, the parties again9 discussed the prospect of J.B. alternating years between his parents , with Petitioner documenting in his notes of their call that Respondent continued to oppose “any plan for [J.B.] to alternate between Germany and [ the ] USA,” because she believ ed that it “put[] too much pressure on [J.B.] to go ba ck and forth” and “insist[ ed ] upon more consistency.” J.A. 156

- 58

. While the dispute between the parties over J.B.’s long

term residency arrangements was ongoing

, Respondent filed
p etition s for divorce and custody and , at the end of May, the Family Court in Allegheny County , Pennsylvania issued an interim custody order that , in terms of physical custody, allowed J.B. to continue to reside with the Respondent, pending a final custody determination

, an d granted Petitioner visitation over the summer and holidays

. On June 9, Petitioner informed Respondent that he had found a good rate for J.B. to return to Berlin on June 19 and that he wanted J.B. to stay in Berlin and go to school ther e “like we planned.” J.A. 144. Respondent objected on the grounds that , under the interim custody order, any trip to Berlin would only be for a visit

, not for the school year

, and that J.B., in any event

, was committed through August 3 to attend robotics and other summer camps

, which Petitioner had not told her to cancel and for which the cancellation deadline had then passed

. Declaring that the interim custody order was “not valid

, ” Petitioner “ demand [ed] that [J.B.] return on 19 June

, ” J.A. 143 , and re iterated t hat he was looking at tickets for both Respondent and J .B., even though Respondent objected that

“

. . . it sounds like yo u are planning to abduct [J.B.], ” and that Petitioner should “ contest the court’s decision . . . legal [l]y

, ”10 J.A. 143

. After a few additional exchanges in which Respondent sought assurance from Petitioner about the length of J.B.’s visit before she would consent to his return to Germany, Petitioner stated that he was “still waiting to hear anything more from the mediators

. ” J. A. 140. The record reflects no additional email communication s between the parties

. On July 6, 2016, Petitioner filed a petition in the United States District Court for the Western District of Pennsylvania

, seeking J.B.’s return to Germany under the Hag ue Convention.

II. District Court Proceedings

The District Court held a two

- day bench trial in mid

August. 2 In addition to the above

- referenced emails and the testimony of Petitioner and Respondent

, the trial record included testimony and documentation offered by J.B.’s teacher, swim coach, parents of J.B.’s school friends, and Respondent’s friends

, related to J.B.’s acclimatization to Pittsburgh

, as well as written statements from Petitioner’s brother and friends and acquaintances in Germany, indicatin g they understood that J.B. was to return to Germany for the

2 Prior to the hearing, the parties were referred to mediation. Unfortunately, mediation was unsuccessful. While mediatio n enables parents, who are well

- positioned to know the needs of their child, to forge a resolution that best serves the child’s interests, a court reviewing a Hague Convention petition has the more limited mandate of “restor[ing] the status quo that existe d prior to the wrongful . . . retention.” Didon v. Dominguez Castillo , 838 F.3d 313, 320 (3d Cir. 2016) (internal quotation marks omitted)

.11 2016

- 2017 school year

. With regard to the testimony of Petitioner and Respondent, the District Court found Respondent generally to be more credible. Of the written
statements offered by Petitio ner, only one was based on a conversation in which Respondent was present, and the rest were based on Petitioner’s representations to the declarants. The District Court accorded these statements “diminished weight” and “minimal significance,” on the groun d s that they were “the product of a concerted effort by Petitioner” and that “several” of the letters “merely . . . parrot[ed] language directly suggested by Petitioner.” Blackledge v. Blackledge

, No. 16

- 1004, 2016 U.S. Dist. LEXIS 114543, at *22 (W.D. Pa. Aug

. 26, 2016)

. The District Court also conducted an in

camera interview of J.B.
On August 19, 2016, the District Court entered an order denying the petition, and on August 26, 2016, it issued a Memorandum O pinion in support of its order. 3 See id . at *1

. Its first order of business was to determine the retention date so that it could then consider which forum was J.B.’s habitual residence immediately prior to that date

. R easoning

3 Because the District Court concluded Petitioner did not meet his burden to prove he was entitled to relief, it di d not address any of the affirmative defenses raised by Respondent, which included that J.B. had attained the age and maturity at which it was appropriate to take account of his preferences, that J.B. preferred to remain in Pittsburgh, and that returning t o Germany would expose J.B. to a grave risk of harm. S ee Hague Convention on the Civil Aspects of International Child Abduction art. 13, Oct. 25, 1980, T.I.A.S. No. 11,670; Blackledge , No. 16

- 1004, 2016 U.S. Dist. LEXIS 114543, at *7

- 15.12 that P etitioner himself testified he originally agreed to permit J.B. t o live in Pittsburgh for one year , starting in August 2015 , and that Petitioner had acquiesced to J.B. participating in camps through the summer , the District Court calculated the retention date as August 2016. Id. at *10

- 11 & n.5

. Turning to the questi on of habitual residence, the District Court correctly recognized that it was required to consider both the parents’ shared intent and the child’ s acclimatization. Id. at *11

- 12 ; see Karkkainen v. Kovalchuk

, 445 F.3d 280, 291

- 92 (3d Cir. 2006) . As to sha red parental intent, it concluded there was “no credible evidence” that the parties agreed that J.B.’s stay would be for a “specific duration.” Blackledge , No. 16

- 1004, 2016 U.S. Dist. LEXIS 114543, at *24. And

, considering evidence of J.B.’s activities and expectations up until the August retention date, the Court concluded that J.B. was acclimatized to Pittsburgh

. Id. at *12

- 17, *24. In so finding

, it accorded “significant weight” to J.B.’s in camera interview, including his stated preference for Pitt sburgh, because it found J.B. “to exhibit an unusual degree of maturity and situational awareness

. ” Id. at *12 n.6

, *15

. As it concluded Pittsburgh was J.B.’s habitual residence immediately prior to the August retention date, the District Court held that the retention was not wrongful under the Hague Convention

. I

d. at *25. The consequence of this holding was t hat J.B. could continue to reside in Pittsburgh pending the resolution of his parents’ custody proceed ings before the Allegheny County Family Cou rt. See generally Karkkainen , 445 F.3d at 287.

Petitioner now appeals , seeking to reverse the District Court’s denial of his petition

, with the understanding that a reversal would allow the Allegheny County interim custody order to be vacated, custody pro ceedings to be initiated in13 Germany, and J.B. to reside with Petitioner in Germany pending the resolution of those proceedings.

I I I. Jurisdiction and Standard of Review
The District Court properly exercised jurisdiction under 22 U.S.C. § 9003 (a) , which grants district courts original jurisdiction over claims arising under the Convention. We exercise juris diction under 28 U.S.C. § 1291.
We review the District Court’s factual findings for clear error and review legal conclusions and the application of
t he law to the facts de novo

. Didon v. Dominguez Castillo

, 838 F.3d 313, 319

- 20 & n.13 (3d Cir. 2016). In the context of Hague Convention cases, certain determinations involve mixed questions of law and fact. We have held, for example, that habitual resi dence is a mixed question of law and fact. Feder v. Evans

- Feder , 63 F.3d 217, 222 n.9 (3d Cir. 1995). A nd a lthough our past cases have not addressed the issue in explicit terms , we recognize today that the two factors informing habitual residence, i.e., the parents’ shared intentions regarding the child’s move and the child’ s acclimatization

, themselves involve mixed question s , because those factors depend both on case

- specific fact

- finding s and whether those findings meet the specified legal threshold. See Ornelas v. United States , 517 U.S. 690, 696

- 97 (1996) (explaining that the “issue [of] whether the facts satisfy the [relevant legal] standard ” is a mixed question of law and fact). For mixed questions of law and fact, we must “separate the issue into its respective parts, applying the clearly erroneous test to the factual component, [and] the plenary standard to the legal.” N

. River Ins. Co. v. CIGNA Reinsurance Co. , 52 F.3d 1194, 1218 (3d Cir. 1995).14 I V

. Analysis
The purpose s of the Hague C onvent ion are “to secure the prompt return of children wrongfully removed to or retained in any Contracting State” and “to ensure the rights of custody and of access under the law of one Contracting State are effectively respected in the other Contracting States .” Hague Convention on the Civil Aspects of International Child Abduction art. 1 , Oct. 25, 1980, T.I.A.S. No. 11,670 [hereinafter Hague Convention]

. The Convention was “not designed to resolve international custody disputes

. ” Karkkainen , 445 F.3d at 287 . R ather , in addressing Hague Convention petitions, courts are limited “to restor[ing] the status quo prior to any wrongful removal or retention, and to deter [ring] parents from engaging in international forum shopping in custody cases.” Id; s ee also Did on , 838 F.3d at 320 (explaining that any return remedy merely “seeks to restore the status quo that existed prior to the wrongful . . . retention ” (internal quotation marks omitted) ).
A petitioner who initiate s judicial proceedings for the return of a c hild under the Hague Convention has the burden to prove , by a preponderance of the evidence

, that the child has been wrongfully removed or retained

. 22 U.S.C. § 9003(b) , (e)(1)(A) . The removal or retention of a child is wrongful if:

a it is in breach o f rights of custody attributed to a person . . . under the law of the State in which the child is habitually resident immediately before the removal or retention; and15 b at the time of removal or retention those rights were actually exercised . . . or wou ld have been so exercised but for the removal or retention.

Hague Convention, supra , art. 3. As we have explained in interpreting these provisions, to determine if a petitioner is entitled to relief, the co urt must answer four questions: “ (1) when the r emoval or retention took place; (2) the child’s habitual residence immediately prior to such removal or retention; (3) whether the removal or retention breached the petitioner’s custody rights under the law of the child’s habitual residence; and (4) whethe r the petitioner was exercising his or her custody rights at the time of removal or retention

. ” Yang v. Tsui , 499 F.3d 259, 2 71 (3d Cir. 2007) (citing Karkkainen , 445 F.3d at 287).

Here, as the District Court observed, there was no dispute as to the four th factor, i.e., that Petitioner had custody rights under German law and that he was exercising those rights. But, having determined that the retention date was August 2016 and that J.B.’s habitual residence immediately prior to that date was Pittsburgh, the District Court concluded

, on the basis of the first two factors, that Petitioner had not met his burden of proving a wrongful retention

. 4 Blackledge

, No. 16

- 1004, 2016 U.S. Dist. LEXIS 114543, at *10, *25

. Below we address, first

, Petitioner ’s argume nt that the District Court erred in fixing the retention date

, and , second,

4 As to the thi rd factor, Petitioner made no argument that the retention breached his custody rights under United States or German law. Instead, his argument focused on whether Germany still remained J.B.’s habitual residence at the time of the retention.16 Petitioner’s contention that it erred in determining J.B.’s habitual residence immediately prior to that date

.
A. Retention Date
According to Petitioner

, the District Court erre d in adopting August 2016 as the retention date because Petitioner had withdrawn his consent to J.B. remaining in th e United States prior to August

, when he had “clearly communicate [ d ] [ his ] desire to regain custody ” of J.B

. in the June 9 email deman ding J .B.’s return by June 19 . Appellant’s Br. 21

- 22 (second alteration in original) (quoting Karkkainen , 445 F.3d at 290)

. Respondent , for her part, urges us to adopt the District Court’s August date. We conclude neither June nor August reflect s the proper d ate under our case law.

In Karkkainen we confr onted a situation where the

non custodial parent initially agreed to the child remain ing in the United States indefinitely , but then, in mid

- July, emailed the custodial parent demanding that the child return h ome on August 10, the date for which she had purchased a return flight for the child

, insisting that retention beyond that date would “constitute kidnapping

. ” 445 F.3d at 289

- 90. In determining the retention date, we recited, without adopting, another cou rt’s definition of “ retention date” as the date the noncustodial parent “clearly communicates her desire to regain custody and asserts her parental right to have [ her child ] live with her.” Id. (alteration in original) (emphasis omitted) (quoting Slagenwe it v. Slagenweit , 841 F. Supp. 264, 270 (N.D. Iowa 1993) ) . Assuming this definition applied

, we held that by mid

- July the noncustodial parent had clearly communicated the withdraw al of consent for the child to remain in the United States beyond August 10 and that nothing in the record “suggest[ed] there was confusion about17 [the noncustodial parent’s] opposition after mid

- July.” Id. at 290. Whi le we acknowledged that the non custodial parent had originally agreed to let the child remain in the United State s indefinitely

, id. at 289, and had communicated in mid

July her withdrawal of that consent beyond August 10, we did not adopt the mid

- July notice date as the retention date

, id. at 290 . Nor did we accept the notion that the original agreement for a longe r period vitiated the noncustodial parent’s ability to clearly communicate her desire to regain custody of the child

. Id

. Instead, we recognized that a party may accelerate a retention date by “ withdraw [ ing ] her consent to have [ the child ] remain ” with t he custodial parent , and we then settled on August 10

— i.e., the date on which consent actually expired

— as the retention date. Id. at 290

- 91.
Building on Karkkainen , we hold that the retention date is the date beyond which the noncustodial parent no long er consents to the child’s continued habitation with the custodial parent and instead seeks to reassert custody rights

, as clearly and unequivocally communicated through words, action s , or some combination thereof. That determination is, by necessity, fac t

- intensive and will vary with the circumstances of each case. And while in some cases the notice date and actual expiration date will coincide, in other cases the notice will indicate a future date as the date consent will be withdrawn, in which case tha t latter date, depending on the facts of the case, will constitute the expiration date and, hence, the retention date.

In determining the retention date here , we conclude that the District Court erred by looking solely to Petitioner’s original consent fo r J.B. to reside in Pittsburgh through August 2016 and failing to assess whether Petitio ner’s subsequent communication s, up to and including the filing of18 his Hague Convention petition

, effected a withdrawal of that
consent

. 5 But, c onsistent with Karkkain en , we also reject Petitioner ’s argument in favor of a June 9

, 2016 r etention date, as that date reflects merely Petitioner’s notice of a possible expiration of consent on June 19 , 2016

.
While in Karkkainen we rested on the prospective date of expiration identified in that petitioner’s notice, id. at 290, significant differences between the facts of that case and this one l ead us to conclude that June 19 also does not reflect the proper retention date here . In Karkkainen the noncustodial parent took the affirmative step of purchasing a ticket

, assert ed that any retention beyond the scheduled return date would constitute “kidnapping,” and did not equivocate as to that retention date

. I

d. at 290 . Here
, in contrast, Petitioner only researched the possibili ty of purchasing a ticket ; Respondent, not Petitioner, flagged a concern about “abduct[ion],” J.A. 143; and Petitioner left open the possibility of further negotiations, stating after his demand email that he was “still waiting to hear anything more from
t he mediators,” J.A. 140

. Under these circumstances, we conclude neither June 9 nor June 19 was the retention date, and in the absence of any earlier communication in which Petitioner clearly and unequivocally withdrew his prior consent and sought to reass ert his custody rights, we hold that

5 Indeed, gi ven that the District Court purported to exercise jurisdiction over this case since the filing of the petition on July 6, 2016, an August 2016 retention date would raise concerns about the ripeness of Petitioner’s claim and the jurisdiction of the federal courts to adjudicate it. See generally Thomas v. Union Carbide Agric. Prods. Co. , 473 U.S. 568, 579

- 80 (1985).19 consent expired and J.B. was therefore “retained” on the date Petitioner filed his Hague Convention petition , i.e.

, July 6

.
Below we consider the evidence concerning J.B.’s habitual residence immediately prior to that retention date and whether the District Court erred in its conclusions as to the parents’ shared intent or J.B.’s acclimatization

.
B. Habitual Residence

To determine where a child is habitually resident we “employ a mixed standard of review, accepting [a] district court’s historical or narrative facts unless they are clearly erroneous, but exercising plenary review of the court’s choice of and interpretation of legal precepts and its application of those precepts to the facts.” Didon , 838 F.3d at 320 n .13 (alteration in original) (quoting Feder , 63 F.3d at 222 n.9). The Hague Convention does not define habitual residence

, and we have held that it “is a fact

- intensive determination that cannot be reduced to a predetermined formula and necessarily varies with the circumstances of each case.” Karkkainen , 445 F.3d at 291. That inquiry becomes all the more difficult where “the petitioning parent initially agreed to allow the child to stay abroad for an indefinite duration, but subsequently had second thoug hts about that decision.” Id. Although a difficult inquiry, it is not without guideposts and

our precedent a ssists us in navigating our path . Below we discuss (1) guiding principles from our case law relevant to habitual residence; (2) the record in thi s case concerning shared parental intent; and (3) the evidence of J.B.’s acclimatization

.

1. Principles of H abitual R esidence20 A child’s habitual residence is “the place where [the child] has been physically present for an amount of time sufficient for a cclimatization and which has a degree of settled purpose from the child’s perspective.” Baxter v. Baxter , 423 F.3d 363, 368 (3d Cir. 2005) (internal quotation marks omitted) (quoting Feder , 63 F.3d at 224)

. To assess whether a child’s habitual residence meets this threshold we analyze both the child’s acclimatization and the “shared parental intent”

— a factor t hat is relevant because “the child’s knowledge of [his parents’] intentions is likely to color [his] attitude to the contacts [he] is making” and “a ffect the length of time necessary for a child to become habitually resident or otherwise influence a child’s ability to acclimatize,” and, in addition, because it bear s on the parents’ own intentions “regarding their child’s presence in a particular place .” 6 Karkkainen , 445 F.3d at 292 , 296 (internal quotation marks omitted)

. As a general matter “courts will find no change in habitual residence” where the evidence of shared parental intent reflects that the “child’s initial move from an established habi tual residence was clearly intended to be f or a specific, limited duration. ” Whiting v. Krassner , 391 F.3d 540, 549 (3d Cir. 2004)

. However, we have recognized an exception to this general rule where a move, though temporary, carrie s “a degree of settle d purpose . . . , even if

6 We give some “independent weight to the parents’ present, shared intentions” to “ensure that neither parent is acting unilaterally to alter a joint understanding reached by the parents.” Karkkainen , 445 F.3d at 292 (internal quotation marks omitted).21 such purpose is only for a limited period.” Id. The concept of “ settled purpose, ” then, does not require an intention “to stay . . . indefinitely,” and may in fact be for a “limited period,” precipitated by various motivations, including “[e]ducation, business or profession, employment, health, family or merely love of the place.” Feder , 63 F.3d at 2 2 3

- 2 4

. R egardless of the motivation for the location selected, or whether the stay was meant to be permanent or temporary, “[a]ll that is necessary is that the purpose of living where one does has a sufficient degree of continuity to be properly described as settled.” Id.
As to the relative weight given the parents’ shared intent and the child’s acclimatization, we have held that w hen a child is very young, he “cannot possibly decide the issue of residency,” Whiting , 391 F.3d at 54 8 , and the parents’ shared intent is , thus, “of paramount importance

, ” while acclimatization is secondary

, Karkkainen , 445 F.3d at 296. H owever, once a c hild is old enough “to develop a certain routine and ac q uire a sense of environmental normalcy,” acclimatization becomes the central inquiry. Whiting , 391 F.3d at 550

- 51. Although we have not fixed the age when acclimatization takes on this greater signi ficance, and it necessarily will vary depending on the maturity and cognitive and social abilities of the child in question, we have recognized that a typical four

- year

- old child “certainly has this ability” because he is “able to develop a certain routine and acquire a sense of environmental normalcy” and is “not only aware of those around him, but is able to form meaningful connections with the people and places he encounters each day.” Id

. At that point, because the child has “reached an age where [he is] capable of becoming firmly rooted in a new country,” we attach greater significance to22 acclimatization and give “less weight to shared parental intent.” Karkkainen , 445 F.3d at 296 (internal quotation marks omitted) (quoting Holder v. Holder , 39 2 F.3d 1009, 1119 (9th Cir. 2004) ).23 2

. The P arents’ Shared I ntent In T his C ase

Here
, the District Court declined to apply the presumption that there is, ordinarily, no change in habitual residence when the child’s move is for a “specific, limited duration” because it found that there was “ no credible evidence ” that the parties had an agreement that J.B.’s stay in Pittsburgh would be for a “specific duration

. ” Blackledge

, No. 16

- 1004, 2016 U.S. Dist. LEXIS 114543, at * 23

- 25 (quoting Karkkainen , 445 F.3d at 2 91 n.3)

. We agree with Petitioner that t his finding was clearly erroneous, given the evidence on this record that there was such an agreement

. But because that evidence overwhelmingly demonstrates the parties intended J.B.’s residence in Pittsburgh, albe it of specific, limited duration, to carry “a degree of settled purpose,” Whiting , 391 F.3d at 549, we nonetheless conclude that the “shared parental intent” factor favors the United States as J.B.’s habitual residence.

At the outset, we cannot agree w ith the District Court that there was no credible evidence that the parties had agreed J.B.’s stay in Pittsburgh was intended to be for a specific duration. While the Court acknowledged that the record demonstrated the “existence of an agreement , ” it none theless found that it “does not speak to the specific terms of the agreement,” Blackledge , No. 16

- 1004, 2016 U.S. Dist. LEXIS 114543, at *19, and therefore rejected the notion the stay could be categorized as of specific, limited duration. But we have not required great precision in the terms of the agreement, nor even a specific return date, in order to conclude a case involved an agreed

- upon move of “specific, limited duration. ” Whiting , 391 F.3d at 549. Instead, we24 have considered cases to fall in tha t category where the move

was bounded by even a general time frame

. S ee Yang , 499 F.3d at 272

- 73 ( describing the child’s residence with the father, intended to be for the length of the mother’s recuperation, as “a limited period of time”); Whiting , 391 F. 3d at 542, 549 & n.6 ( discussing the child’s stay with her mother for two years but “no later than October 19, 2003” as “intended to be for a specific, limited duration ” ); see also Feder

, 63 F.3d at 223

- 24 (citing with approval In re Bates
, No. CA 122

- 89, High Court of Justice, Family Div’l Ct. Royal Courts of Justice, U.K. (1989) (framing an approximately three

- month stay with mother, while father
was on a concert tour , as “for a limited period”) )

.
Here
, although the District Court was correct that the
p arties’ email s stop short of identifying a date certain that was originally agreed for J.B.’s return, or similarly “specific terms of the agreement

, ” Blackledge , No. 16

- 1004, 2016 U.S. Dist. LEXIS 114543, at *19, they make clear t hat the parties intended J .B.’s stay in Pittsburgh to be of a “specific, limited duration ,” Whiting , 391 F.3d at 549

. For example, in response to Petitioner ’s references to the alleged “agreement” in his emails in February 201 6
, and his request s that Respondent “keep[] with [their ] agreement that [J .B.] will
return to [Petitioner] for the academic year 2016

- 2017 ,” J.A. 190, Respondent did not reject the notion that there was an agreement or that J.B.’s stay with her in Pittsburgh was intended to be for a limited duration . Rather, she asked Petitioner to “ reconsider ” the agreement, J.A. 172, so that J.B. could stay with her “as a primary caregiver

, ” J.A. 171, rather than requiring him to “yearly adapt[] to living” with a different parent in alternating years, which she believed woul d be “psychologically disadvantageous” for him, J.A.25 177. Indeed, the record is replete with references to the parties’ agreement that “ [J.B.] would go with [Respondent] to Pitt [sburgh] and return to [Petitioner] for [the] 2016

- 2017 academic year. Then b ack to [Respondent] .” J.A. 176; s ee also J.A. 168 (warning Respondent to “prepare [herself] for fulfillment of [their] agreement that [J.B.] returns to [Petitioner] for 2016

- 2017” and reassuring her

, “You’ll have him again in 2017”); J.A. 178 (noting tha t Respondent had not previously expressed concerns for J.B. to “spend alternate years with us when the agreement was made”).

Notwithstanding such error, “ we may affirm on any ground s supported by the record, ” Maher Terminals, LLC v. Port Auth. of N.Y. & N .J. , 805 F.3d 98, 105 n.4 (3d Cir. 2015), and “[w]hen the outcome is clear as a matter of law . . . remand is not necessary

, ” Mahmood v. Gonzales , 427 F.3d 248, 253 (3d Cir. 2005)

. Here, we conclude such an outcome is clear as a matter of law because this case is on all fours with our decision in Whiting v. Kra s sner , 391 F.3d 540 (3d Cir. 2004).

In Whiting , the parents had agreed in writing, after the attack on the World Trade Center in New York City on September 11, 2001 , that the mother and child would leave the United States and live in Canada for two years

— i.e., for a limited duration. 391 F.3d at 542. Two months into the move, however, the father changed his mind and removed the child to the United States. Id. at 543. A s the child there was only s ixteen months old

, see id. at 542

- 43, we focused on shared parental intent, and not acclimatization, and we concluded that the child’s habitual residence was Canada

, id. at 551

- 52

. After observing the parties intended for the m other and child

, albeit for that specified period

, to put down roots and take on the normal pattern of residential life in Canada

,26 including renting an apartment near the mother’s family members , looking into childcare programs, and applying for necessary documentation, such as a med ical car d

, id. at 542, we concluded the move was accompanied by a “degree of settled purpose

, ” i d. at 549

. Given that purpose, we observed, the fact that the mother and child’s Canadian residence was planned for two years “d[id] not in any way diminish th e parties’ settled intention that the two were to remain in Canada for at least two years” and “in no way hinder[ed] the finding of a change in habitual residence.” Id. at 550. In reaching our holding, we also rejected the father’s argument that Canada c ould not have become the child’s habitual residence because there was no shared intent to abandon the United States, and we recognized that “abandonment,” as the flipside of “habitual residence,” could also be for “a definite and extended period,” i.e., un til the child resumed her habitual residence in the abandoned country

, as scheduled. 7 Id.

In Whiting

, we also relied heavily upon and cited approvingly to a British case that is even more analogous to J.B.’s case. Id. at 547 (citing In re Bates , No. CA 122

- 89, High Court of Justice, Family Div’l Ct. Royal Courts of Justice, U.K. (1989) ); s ee also Feder , 63 F.3d at 222

- 24 (quoting In re Bates ). There, the father was a mus ician who

7 In Whiting , we held that Canada had become the child’s habitual residence based only on the parties’ shared intent. 391 F.3d at 550

- 51. Her e , in contrast

, not only the shared parental intent

, but also acclimatization

, favor the

c ountry of the custodial parent, s ee infra Part IV.B.3, making this an even stronger case for the United States as J.B.’s habitual residence.27 travelled extensively, and the mother and child “had toured with father fo r the majority o f the girl’s life to that point. ” Whiting , 391 F.3d at 547 n.5. Though London “was the family’s home base,” the parents decided that the mother and daughter would live in New York while the father toured the Far East
, but after only two d ays, the father directed the nanny to bring the girl back to London

. Id. The c ourt reasoned that the accommodations made in New York to which father had agreed, “however acrimoniously,” for the three months before father “return[ed] to London amounted to a purpose with a sufficient degree of continuity to enable it properly to be described as settled

. ” Feder , 63 F.3d at 22 4 (quoting In re Bates )

. The child’s habitual resid ence, therefore, was New York

. Id. at 223

- 24 (citing In re Bates )

. Likewise, here, it is evident that J.B.’s move to the United States, although of limited duration, was intended by both Petitioner and Respondent to be accompanied by a degree of “settled purpose.” Whiting , 391 F.3d at 550. The record reflects that J.B. moved to Pittsb urgh in August 2015 for the purpose of assuming a full and normal life of an eight

year

- old boy during the intended period of his stay, making long

- term friends and plans, developing routines and a sense of environmental normalcy, exploring h is city and ot her parts of the C ommonwealth, and putting down roots

, not only for the 2015

- 20 16 school year, but also, per the parents’ express agreement , for future alternating years, interspersed with the years he would be living with Petitioner in Germany

. Under the se circumstances

, as in Whiting , the fact that the parties understood that J.B. would return to Germany “d[id] not in
any way diminish . . . the parties’ settled intention” that he was to remain in the United States for at least a year, settling into a nor mal routine , and the fact that J.B.’s stay was28 intended to be of a limited duration “in no way hinder[ed]” a finding that the United States was his habitual residence during that time. Id.
Petitioner disputes this interpretation of the record, arguing that this case more closely resembles that addressed by t he Ninth Circuit in Mozes v. Mozes , 239 F.3d 1067 (9th Cir. 2001)

. There the children, Israeli residents, traveled with their mother to the United States for a fifteen

- month visit to “partake of Ame rican culture,” id. at 1069, in what the court analogized to a “study[] abroad” program, id. at 1083. A year into that visit, however, the mother filed for divorce and retained the children in the United States. Id. at 1069. In rejecting the mother’s ar gument that the United States had become the children’s then

- habitual residence, the Ninth Circuit concluded that, when the children moved to the United States, the “normal expectation

, ” shared by both the parents and the children, was that the family woul d reunite in their home in Israel and that Israel would , therefore, remain their habitual residence

. Id. at 1083. As the court explained, the parents and the children were Israeli citizens ; they ha d lived all their lives in Israel and entered the United States on a temporary visa; and neither parent had a prior connection to the United States

. Id. at 1069, 1082.
The record in J.B.’s case paints a very different picture. Petitioner and R e sp ondent did not intend J.B.’s stay in Pittsburgh as a “study[] abroad” program or a transient “American cultur[al]” visit

. Id. at 1069, 1083. On the contrary, when Respondent and J.B. moved to the United States, J.B. was returning to a country and culture with which he was already familiar and a city in which he had previously lived for two years

— a city that, by the time of the retention date, was the longest and most stable residence he had known29 in his fairly nomadic early years ; in addition to having extended family in the United States, J.B. was a United States

c itizen , as was his father, and his mother was a lawful permanent resident; Respondent and J.B. had resided in Germany for only two years between the ir two residences in Pittsburgh ; within the first month of J.B.’s residence in Pittsburgh

, his father made e fforts to secure a job in the United States and elsewhere , indicating at one point that he felt “dirty” that J.B. might not have a home to return to in Germany at the end of that year

, J.A. 200 ; at the time of the
move, both Petitioner and Respondent recog nized their marriage had become acrimonious

, and according to Respondent, whom the District Court generally found more credible

, the parties had agreed to divorce and it was only “a matter of time [as to] when,” J.A. 421

- 22 ; and the parents’ emails are exp licit that they intended to continue living separately in future years and for J.B. to alternate between them, spending the 201 5

- 20 1 6 academic year in Pittsburgh, the 201 6

- 20 1 7 academic year in Germany, and the 201 7

- 20 1 8 academic year back in Pittsburgh

. Thus, this is not a case, as in Mozes , where the noncustodial parent’s country had served to that point as their “home countr[y]” or where it c an be said the “normal expectation” of the parties was that they would
return to that country to live as a family unit

. See Mozes , 239 F.3d at 1083.
Petitioner, argues, however, that we should disregard those portions of the parents’ communications reflecting that they had agreed that J.B. would “spend alternate years with [them] when the agreement was made,” J. A. 178, or that J.B. would be retu rning to Pittsburgh for the 2017

- 20 18 school
year , and that we should limit our consideration of the parents’ agreement to those excerpts in which they discuss30 J.B.’s return to Germany for the 201 6

- 20 1 7 school year

. This we decline to do . F or as we have repeatedly recognized, the parents’ agreement as to the allocation of custody between them is highly relevant to the determination of “shared parental intent.” See, e.g., Karkkainen , 445 F.3d at 292

- 93

, 296

- 97 ; Whiting , 3 91 F.3d at 54 8

- 51 . After all, the main

reason we look to “shared parental intent” as part of our inquiry is its likelihood “to color [the child’s] attitude to the
contacts [he] is making” and to “affect the length of time necessary for a child to become h abitually resident or otherwise influence a child’s ability to acclimatize”

— factors relevant to the determination whether the move carried a “settled purpose ‘from the child’s perspective.’” Karkkainen

, 445 F.3d at 292 , 296

. For those reasons, where the parents have agreed, in connection with a child’s move to a given residence, that the child will henceforth split time between them, and, thus, is expected to return to that residence at regular intervals going forward, that shared parental intent will und oubtedly affect the child’s attitude, expectations, plans, and sense of purpose in undertaking the move to that residence. 8

8 The significance of the parents’ forward

- looking intent in this circumstance is different than in those cases where courts have observed that the formation of a n intent ion to move does not convert the intended future residence into a

“ habitual residence. ” See, e.g.

, Feder

, 63 F.3d at 222 (citing Friedrich v. Friedrich , 983 F.2d 1396 (6th Cir. 1993) (holding that a mother’s intention to move the child to the United States did not make the United States the child’s habitual residence prior to the move)). Where a child is
actu ally living in a given residence , and we are tasked with31 Indeed, Mozes , by its terms, distinguished the “rare situation[s] where someone consistently splits time more or less evenly betwee n two locations, so as to retain alternating habitual residences in each.” 239 F.3d at 1075 n.17 (citing Johnson v. Johnson , 493 S.E.2d 6 6 8 (Va. Ct. App. 1997) ) ; se e also id. at 1084 n.50 (explaining that where a child “spen t regularly alternating periods with each parent . . . , [ he ] might thus have acquired dual habitual residence”). And more recently the Ninth Circuit again observed in dictum that, where the child splits time between his parents’ countries of residence, he may be deemed to have “consec utive, alternative habitual residences” where supported by the facts. Valenzuela v. Michel , 736 F.3d 1173, 1178

- 79 (9th Cir. 2013) ( noting that the father also could have prevailed by showing that the father and the mother “shared a settled intention to

a bandon Mexico as the [children ’ s ] sole habitual residence”).

Likewise, the courts of other Hague Convention member states have consistently recognized that the existence of a so

- called “shuttle custody” arrangement, in which a child splits time between h is parents’ countries of residence, bears on the determination of habitual residence. See, e.g.

, Wilson v. Huntley , 2005 Carswell Ont. 1606 , at ¶¶ 8, 32, 50 (Can. O nt

. S up

. C t

. J. ) (WL) (holding that, where the child split her time in three

- to

- six month i ntervals between the mother and the father’s homes, developing “similar social and family bonds in each State,” and where the “parents clearly intended

determining whether th e move to it wa s accompanied by a settled purpose, the parents’ and child’s expectations that the child will return to that residence on a regular basis in the future is necessa rily relevant to the child’s attitude regarding the move itself.32 to share custody of [the child], in the legal sense and in the sense of physical, residential custody

, ” the child “could have consecutive alternative habitual residences in two different States at separate times ”); J. v. J. [HFD] [Supreme Administrative Decision] 1995 case no. 75 0 5

- 1995 (Swed.)

, translated at https://assets.hcch.net/incadat/fullcase/0080.htm ( holding that

, where the parents agreed to be responsible for the child “on an alternate basis” and to “share [the child’s] de facto care

, ” the child was habitually resident in her mother’ s home country, where s he was residing immediately prior to the ret ention, because t he child had spent the last two years there and “ha[d] adjusted to circumstances in the place where she [wa]s living”).

While we have observed in dictum that the concept of “alternating habitual residence” would appear to comport with th e Hague Convention so long as “a child has only one habitual residence country at any given time,” Didon , 838 F.3d at 322 n.20, w e have not had prior occasion to address the relevance or weight of an agreement that a child split time between two parents

. In doing so now, we emphasize that the parents’ shared intent as to the custody arrangement between them is probative

—

but not dispositive

— in the determination of habitual residence. That is, we agree with the observation that “where residence with two par ents is divided equally

, it

. . . [ is ] unreal, in the absence of other differentiating factors, to see the residence with one parent as primary and stays with the other parent as interruptions.” Watson v. Jamieson , 1997 Fam. L.R. 11 , 14 (Scot.). At the s ame time,

w e eschew any suggestion that an agreement to alternate habitation between parents automatically equates to “alternating habitual residences.” Indeed, any such categorical approach to shared custody or one

- size

- fits

- all33 framework for habitual re sidence would be inconsistent with our case law, which rejects the application of a “predetermined formula” to Hague Convention cases, Karkkainen , 445 F.3d at 291, and with the Convention, which contemplates a fact

- specific approach and encourages a “flexi ble interpretation” of its terms, Eliza Perez

- Vera, Explanatory Report

, in 3 Hague Conference on Private International Law, Acts and Documents of the Fourteenth Session, Child Abduction 426, 446 (1982)

. 9

Instead, we view a parent al agreement that a child will split time between the parents’ countries of residence as a significant consideration , but as one among others, informing the “necessarily fact

- intensive and circumstantially based” inquiry a court must undertake to determine whether a child’s

move w as accompanied by a “degree of settled purpose.” Whiting , 391 F.3d at 547

- 48

. Approaching the inquiry in this way, we respect both our precedent and Congress’s instruction that we pay heed to “the need for uniform international interpretation of the Conv ention

. ” 22 U.S.C. § 9001 (b)(3)(B)

. Undertaking that inquiry here, we consider, in addition
to the other record evidence discussed above concerning the parents’ shared expectations for J.B.’s move to Pittsburgh in 2015, the parents’ agreement that J.B. would “alternate between Germany and [the] USA” going forward, J.A. 157

,

9 As we previously recognized, “Elisa Perez

- Vera was the official Hague Conference Reporter, and her report is generally recognized as the official history and commentary on the Convention.” Whiting , 391 F.3d at 546 n.3 (internal quotation marks omitted)

.34 and, hence, that J.B. would be returning to Germany for only a single academic year before resuming his resi dence in Pittsburgh for the 2017

- 20 1 8 year

. In view of that agreement

an d the totality of the record in this case, it is apparent that J.B.’s 2015 move to Pittsburgh was accompanied, through at least the July 6, 2016 retention date, by the requisite “degree of settled purpose” and that the element of shared parental intent thu s supports the United States as J.B.’s then

- habitual residence. 10 Whiting , 391 F.3d at 549.

3. The R ecord C oncerning J.B.’s A cclimatization
Petitioner asserts two points of error on acclimatization, arguing that the District Court applied the wrong retenti on date and, therefore, improperly considered irrelevant evidence of acclimatization, and that, when the record is limited to the proper time frame, it does not support a finding of acclimatization. While we agree that the District Court mistakenly consid ered post

- retention

- date evidence, we

10 Petitioner ’s argument that J.B. was expected to return to Germany after the year in Pittsburgh is thus beside the point. Although Petitioner accurately catalogues the evidence supporting that expectation

— e.g., the letter to J.B.’s school requesting a one

- year leave of absence and stating that J.B. would return for the 2016

- 2017 academic year; the three

year German visas the parties and J.B. obtained before the Respondent and J.B. left the country; and that J.B. left some of his belongings behind in Germany

— that evidence is entirely consistent with the parties’ agreement that J.B. was to spend alternating years with each parent and that, during his year in Pittsburgh , the United States was J.B.’s habitual residence.35 have no trouble concluding that error was harmless given the substantial record concerning acclimatization as of the correct retention date. See generally Winston ex rel. Winston v. Children & Youth Servs. of Del. Cty

. , 948 F.2d 1380, 1391 n.7 (3d Cir. 1991) (holding that the court’s consideration of inadmissible hearsay was harmless error where there was “sufficient evidence without [the improperly admitted evidence] to support the district court’s conclusion”).

The evidence of J.B.’s acclimatization to Pittsburgh as of July 6 , 2016 is overwhelming. He had a tremendously successful academic year, earning nearly all As and overcoming an initial reading deficiency while demonstrating “dramatic improvement” over the ye ar. J.A. 32 9

, 333, 451. In addition, J.B. made friends “easily” and was, according to his teacher, “well

- adjusted” overall. J.A. 330, 334. J.B. also enjoyed numerous activities outside of school, including soccer, swim team

, and a robotics club, which he was handpicked to join by a fellow classmate. Over the course of the year, J.B. learned how to successfully program a robot to complete missions, despite feeling as though the task was impossible when he first started. And on his swim team J.B.
master ed each of the competitive strokes, and was competing by the end of the year, looking forward to stepping up into the next group the following year.

The record, likewise, reflects that J.B. was sufficiently mature to form “meaningful connections with the people and places he encounter [ ed ] ” in Pittsburgh. Whiting

, 391 F.3d at 550

- 51

. In a credibility determination, to which we defer absent clear error, Cooper v. Harris , 137 S. Ct. 1455, 1468 (2017), the District Court found that J.B. “exhibit[ed] an

unus ual degree of maturity and situational awareness,” and therefore accorded “significant weight” to J.B.’s statements36 that he was looking forward long

- term to moving into a house and getting a dog in Pittsburgh

, that he understood “his place in Pittsburgh,” that he preferred living in Pittsburgh over Berlin because of his quality of life in the United States and because he had “more and better friends in Pittsburgh.” 11 Blackledge , No. 16

- 1004, 2016 U.S. Dist. LEXIS 114543, at *12 n.6, 14

- 15

. Th e in camera in terview thus further support s the District Court’s conclusion, based on the record as a whole, that J.B. had “formed meaningful connections with the people and places he encountered,” i d. at *16 (quoting Karkkainen , 445 F.3d at 294 ( brackets omitted)), and “ha[d] attained a sufficient degree of continuity to be properly described as settled,” i d. (internal quotation marks omitted) (quoting Yang , 499 F.3d at 273).

While Petitioner argues the District Court relied heavily on evidence of activit ies post

- dat ing the July 6 retention date

, that evidence, on inspection

, reduces to three minor points of testimony: J.B.’s swim team that ran from September 2015 through the end of July 2016

, a summer reading challenge that ran from May 24 through August 31, and J.B.’s summer camps . Petitioner argues that any consideration of these activities constituted reversible error,

11 We consider J.B.’s preference for Pittsburgh here because a child’s expressed preference for a country may, considering his age and maturity, be a further indication that the child has acclimatized to that country, see Karkka inen
, 445 F.3d at 294

- 95, regardless of whether that preference as stated would satisfy the “wishes of the child” defense or exception outlined in the Hague Convention, s ee Yang , 499 F.3d at 278 (citing Hague Convention, supra , art. 1 3 )

.37 but we are not persuaded that the District Court erred, much less that such error was prejudicial. 12 For example, while the reading challenge extende d through August 31, J.B. completed it on July 5, prior to the retention date. And while J.B.’s participation on the swim team carried over through the end of July

, the testimony related to J.B.’s involvement dating back to September 2015, with no mention of specific events between July 6 and July 31 . Even the evidence regarding

summer camps is relevant to the extent it inform ed J.B.’s expectation s and aspirations before July 6. Moreover, any

error in the District Court’s consideration of this evidence

w as harm less because the post

- retention

- date activities were merely duplicative and cumulative of other evidence in the record concerning those same activities. See Howmet Aluminum Corp. v. Hartford Accident and Indem. Co. , 665 F.2d 476, 47 8 (3d Cir. 1981) (citing Fed. R. Evid. 61) (holding that consideration of inadmissible evidence that is merely cumulative of properly admitted evidence is not grounds for remand or reversal).
In sum, given the extensive record evidence of J.B.’s success in school, his par ticipation in various activities and sports, his many friendships , his experiences at cultural, entertainment, and sporting events, and his own stated preference for the United States, to which the District Court afforded “significant weight” because of “t he degree of

12 Because we conc lude that any error in consider ing evidence beyond July 6 was harmless, we need not address the Respondent’s argument that the Petitioner waived his objections to the District Court’s consideration of it because he failed to preserve such objections at var ious points in the proceedings.38 maturity and situational awareness” J.B. exhibited, Blackledge , No. 16

- 1004, 2016 U.S. Dist. LEXIS 114543, at *12 n.6, the District Court did not clearly err in its fact

finding related to J.B.’s acclimatization, nor did it commit legal error in its determination that J.B. was acclimatized to the United States at the time of retention.

V. Conclusion
Because the parents’ shared intent was for J.B. to move to the United States with a “degree of settled purpose,” Whiting , 391 F.3d at 549, and bec ause J.B. had acclimatized to the United States by the date of retention, we agree with the District Court’s holding that the United States was J.B.’s habitual residence immediately prior to the retention date and that the retention therefore was not wrong ful under the Hague Convention. Accordingly, we will affirm the order of the District Court

.